Archive for November, 2014

Count down the days until the New Year with the OA-ICC!

Each day of December you will find a short story on the OA-ICC news stream, highlighting an ocean acidification project or effort, demystifying a strange ocean acidification acronym or reminding you of a useful ocean acidification resource!

Look out for the OA-ICC December calendar – coming up December 1st!

Ocean acidification reshapes the otolith-body allometry of growth in juvenile sea bream

The effects of elevated CO2 partial pressure (pCO2) on otolith calcification and on the coupling between somatic and otolith growth were investigated in juvenile gilthead sea bream Sparus aurata. Six-month old individuals were raised during seven weeks under four pCO2 conditions set according to projected future ocean acidification scenarios. Body and otolith biometric parameters were measured throughout the experiment along with the otolith biomineralization monitored using a radiotracer technique based on 45Ca incorporation. Sea bream exhibited somatic growth resilience to all treatments. In contrast, increased growth rate and shape complexity of otoliths were observed with a pHT drop from 8.1 to 7.5. Hypercalcification was observed under lowered pH, with a rate of calcium incorporation increasing by up to 18% between pHT 8.1 and pHT 7.7. This work highlighted an uncoupling of otolith and body growth of juvenile sea bream within 40 days at pHT 7.9 projected to be reached by the end of the century. As the otolith is an essential tool used in reconstructing fish life history, this work suggests that information resulting from otolith studies should be interpreted with caution with respect to the potential impacts that ocean acidification projected modifications could have on otolith biomineralization.

Continue reading ‘Ocean acidification reshapes the otolith-body allometry of growth in juvenile sea bream’

The pH is falling! Oysters and economics on the Hill

That’s right – the pH is falling. The pH of our oceans to be exact.

Yesterday afternoon, WWF-Canada and the All Party Ocean Caucus hosted an Oceans on the Hill event to highlight this global issue, which is generally referred to as ocean acidification.

Ocean acidification takes place when carbon dioxide in our atmosphere is absorbed by the ocean, lowering the pH. This naturally occurring process is accelerated by our fossil fuel emissions, resulting in global oceans that are now 26 per cent more acidic than before the industrial revolution.

Parliamentarians, staffers, industry reps, and NGOs gathered in Centre Block to hear from Bill Dewey, Manager of Public Policy and Communications for Taylor Shellfish Farms. Bill came to Parliament to give us an on-the-ground report of ocean acidification’s impacts on the shellfish industry in the Pacific Northwest. As WWF’s CEO David Miller remarked, Bill helped us to “make the connection between the global and the local.”

Continue reading ‘The pH is falling! Oysters and economics on the Hill’

Behavioural responses to simulated bird attacks in marine three-spined sticklebacks after exposure to high CO2 levels

The rising partial pressure of CO2 (pCO2) in oceanic water, termed ocean acidification, is an impending threat to marine life and has previously been shown to affect several aspects of fish behaviour. We evaluated the behavioural response to a simulated avian predator attack and lateralisation in three-spined sticklebacks (Gasterosteus aculeatus) after 10 and 20 days of exposure to present-day pCO2 (400 μatm) or elevated pCO2 (1000 μatm). We show that elevated pCO2 lead to reduced behavioural lateralisation. However, no major differences in the sheltering response after an overhead avian attack were observed; fish from both treatments exhibited similar and strong responses. Compared to fish exposed to high pCO2, the control fish took longer time to freeze (i.e., stop moving) after attack at day 20 but not day 10. The freezing duration was significantly reduced between day 10 and day 20 in elevated pCO2, whereas no such reduction was observed in the control-group. However, no significant differences between treatment groups were detected at day 20. These results demonstrate that behaviour is indeed altered by high CO2 levels, although the general responses to avian predation stimuli remain similar to those of unexposed fish, indicating that some predator avoidance behaviours of three-spined sticklebacks are robust to environmental disturbance.

Continue reading ‘Behavioural responses to simulated bird attacks in marine three-spined sticklebacks after exposure to high CO2 levels’

Oyster farmers and ocean acidification (text & video)

The ocean is so acidic that it is dissolving the shells of our baby oysters,” says Diani Taylor of Taylor Shellfish Farms in Shelton, Washington. She and her cousin Brittany are fifth-generation oyster farmers, and are grappling with ocean waters that are more acidic and corrosive than their fathers, grandfathers, and great-grandfathers knew.

Continue reading ‘Oyster farmers and ocean acidification (text & video)’

Design, construction, and operation of an actively controlled deep-sea CO2 enrichment experiment using a cabled observatory system

We describe the design, testing, and performance of an actively controlled deep-sea Free Ocean CO2 Enrichment (dp-FOCE) system for the execution of seafloor experiments relating to the impacts of ocean acidification on natural ecosystems. We used the 880 m deep MARS (Monterey Accelerated Research Initiative) cable site offshore Monterey Bay, California for this work; but the Free Ocean CO2 Enrichment (FOCE) system concept is designed to be scalable and can be modified to be used in a wide variety of ocean depths and locations. The main frame is based on a flume design with active thruster control of flow and a central experimental chamber. The unit was allowed to free fall to the seafloor and connected to the cable node by remotely operated vehicle (ROV) manipulation. For operation at depth we designed a liquid CO2 containment reservoir which provided the CO2 enriched working fluid as ambient seawater was drawn through the reservoir beneath the more buoyant liquid CO2. Our design allowed for the significant lag time associated with the hydration of the dissolved CO2 molecule, resulting in an e-folding time, τ, of 97 s between fluid injection and pH sensing at the mean local T=4.31±0.14 °C and pHT of 7.625±0.011. The system maintained a pH offset of ~0.4 pH units compared to the surrounding ocean for a period of~1 month. The unit allows for the emplacement of deep-sea animals for testing. We describe the components and software used for system operation and show examples of each. The demonstrated ability for active control of experimental systems opens new possibilities for deep-sea biogeochemical perturbation experiments of several kinds and our developments in open source control systems software and hardware described here are applicable to this end.

Continue reading ‘Design, construction, and operation of an actively controlled deep-sea CO2 enrichment experiment using a cabled observatory system’

Ocean acidification (audio)

The most serious, debilitating circumstance affecting the ocean today may be acidification, the changing pH or acid balance in the water column with devastating impacts on the marine food chain, species migration and reproduction. In this episode of World Ocean Radio, host Peter Neill will report on the recently-released 20 Facts About Ocean Acidification.

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Ocean acidification report vote delayed

AUGUSTA — The commission studying the impacts of ocean acidification on the state’s commercial fisheries is asking legislative leaders for permission to meet one more time before issuing the final version of its report.

The Legislature established the mellifluously named Commission to Study the Effects of Coastal and Ocean Acidification and Its Existing and Potential Effects on Species That Are Commercially Harvested and Grown along the Maine Coast on April 30. The authorizing legislation called for the commission to deliver its final report to the Marine Resources Committee by Dec. 5.

The 16-member commission was scheduled to vote on a draft version of the report at what was slated to be its final meeting on Nov. 10. Instead, said staff person Curtis Bentley, the commissioners will ask the Legislature’s Legislative Council for authority to meet once more, at the beginning of December, to review proposed changes to the draft and vote on a final version.

Continue reading ‘Ocean acidification report vote delayed’

CT scans of coral skeletons reveal ocean acidity increases reef erosion (text & video)

Photo by N. Silbiger

Photo by N. Silbiger

Coral reefs persist in a balance between reef construction and reef breakdown. As corals grow, they construct the complex calcium carbonate framework that provides habitat for fish and other reef organisms. Simultaneously, bioeroders, such as parrotfish and boring marine worms, breakdown the reef structure into rubble and the sand that nourishes our beaches. For reefs to persist, rates of reef construction must exceed reef breakdown. This balance is threatened by increasing atmospheric carbon dioxide, which causes ocean acidification (decreasing ocean pH). Prior research has largely focused on the negative impacts of ocean acidification on reef growth, but new research this week from scientists at the Hawai’i Institute of Marine Biology (HIMB), based at the University of Hawai’i – Mānoa (UHM), demonstrates that lower ocean pH also enhances reef breakdown: a double-whammy for coral reefs in a changing climate.

Continue reading ‘CT scans of coral skeletons reveal ocean acidity increases reef erosion (text & video)’

Reefs shift from net accretion to net erosion along a natural environmental gradient

Coral reefs persist in an accretion-erosion balance and ocean acidification resulting from anthropogenic CO2 emissions threatens to shift this balance in favor of net reef erosion. Corals and calcifying algae, largely responsible for reef accretion, are vulnerable to environmental changes associated with ocean acidification, but the direct effects of lower pH on reef erosion has received less attention, particularly in the context of known drivers of bioerosion and natural variability. This study examines the balance between reef accretion and erosion along a well-characterized natural environmental gradient in Kāne‘ohe Bay, Hawai‘i using experimental blocks of coral skeleton. Comparing before and after micro-computed tomography (µCT) scans to quantify net accretion and erosion, we show that, at the small spatial scale of this study (tens of meters), pH was a better predictor of the accretion-erosion balance than environmental drivers suggested by prior studies, including resource availability, temperature, distance from shore, or depth. In addition, this study highlights the fine-scale variation of pH in coastal systems and the importance of microhabitat variation for reef accretion and erosion processes. We demonstrate significant changes in both the mean and variance of pH on the order of meters, providing a local perspective on global increases in pCO2. Our findings suggest that increases in reef erosion, combined with expected decreases in calcification, will accelerate the shift of coral reefs to an erosion-dominated system in a high-CO2 world. This shift will make reefs increasingly susceptible to storm damage and sea-level rise, threatening the maintenance of the ecosystem services that coral reefs provide.

Continue reading ‘Reefs shift from net accretion to net erosion along a natural environmental gradient’

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Ocean acidification in the IPCC AR5 WG II

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